1. Field of the Invention
The present invention relates to the field of mechanical drives for vehicles, and more particularly to a novel variable drive mechanism for powering the drive wheel of a cyclic type vehicle employing a novel means utilizing a gear speed change and drive shaft to power the rear wheel of the vehicle.
2. Brief Description of the Prior Art
In the past, it has been the conventional practice to employ a sprocket and chain drive for powering the rear wheel of a vehicle, such as a bicycle or the like. Such a chain and sprocket drive generally includes a derailleur system for permitting the driver to selectively engage a variety of sprocket gears with the chain in order to derive a variety of power combinations. Such a system generally includes a manual shifting means which is connected to the derailleur mechanism so that the chain is physically lifted from one driven sprocket wheel to another sprocket gear. The selection of sprocket gears and, therefore, speed and power is determined by the selection of sprocket gears powering the drive shaft of the rear wheel. Limited selection of gear or gear ratios is permitted by the drive gear which is generally under pedal control by the user. Furthermore, conventional sprocket and chain drive is subject to chain breakage and in many instances, the chain will "jump" off of the teeth of the drive or driven sprocket gear. The number of drive speeds is limited in a derailleur type system and shifting of gears from one speed to another requires movement of the vehicle so that no gear changes are permitted while the vehicle is stationary.
In other instances, it is difficult to remove the rear wheel for tire changes, repairs or the like since the derailleur mechanism is very complex and generally requires skill for reassembly.
Therefore, a long-standing need has existed to provide a variable drive mechanism for cycle-type vehicles which eliminates the necessity for a chain and sprocket drive system. Such a novel solution may incorporate a gear speed change and drive shaft connecting the drive mechanism to the rear driven wheel whereby a multiplicity of gear speeds may be selected by the driver in a convenient manner. Such a gear selection system includes utilizing the drive gear as well as the driven gear for speed control as well as an intermediate transmission connecting the drive and driven gears together.